Scientists at the Massachusetts Center for the Application of Technology in Medicine (MGH-CEM) have developed a simple method of keeping water and water-based solutions in a liquid state at temperatures well below the normal "freezing point" for very long periods of time. While they did it with just a few ounces, their approach, described in Nature Communications, could one day provide safe, long-term preservation of blood cells, tissues and organs, and improve food safety.
“Water and other aqueous solutions, in the volumes we encounter every day, usually freeze when cooled below the freezing point of 0 degrees Celsius,” says Burke Usta, Ph. D. from MGH-CEM, co-author of the work. “Our approach, which we have called 'deep hypothermia,' is to coat the surface of such a liquid with a solution that does not mix with water, such as mineral oil, to block the interaction between water and air. This surprisingly simple, practical, and inexpensive approach to supercooling liquids over extended periods could open up many methods for preserving food and medicine, as well as enabling fundamental experiments not previously available.”
Can organs be frozen for a long time?
In most real environments, water and aqueous solutions begin to freeze when the temperature reaches below zero, and ice crystals form randomly where liquids come in contact with air or various impurities in the solution. Subcooling, which keeps the liquid at a low temperature without crystallization, can only be done in small volumes and for short periods of time using high pressure equipment that is expensive and can damage tissues or other biological materials.
Lowering the temperature of any biological material - during, for example, cold storage of perishable food and organs for transplantation - slows down metabolic and other reactions. Hypothermia prolongs this metabolic slowdown without damage caused by ice crystallization. The scientists found that sealing the surface of a small (1 ml) sample of water with a hydrocarbon-based oil such as mineral oil, olive oil, or paraffin oil can suppress ice formation in temperatures as low as -13 degrees for a week. In the course of experiments with more complex oils and simple hydrocarbons, such as alcohols and alkanes, they managed to keep 1 ml of samples of water and cell suspension supercooled to -20 degrees for 100 days and 100 ml of samples for a week.
Ilya Khel